/* This javascript is only made to make a quick
 * demonstration of the form states when validating.
 * The code itself is a quick hack and nothing that 
 * should be used in the real world (wide web).
 * I'm not proud of this...
 */

const testForm = document.getElementById("test-form");
const formMessageHolder = document.getElementById("form-message");
const nameField = document.getElementById("name");
const emailField = document.getElementById("email");

testForm.addEventListener("submit", event => {
	event.preventDefault();
	const nameValue = nameField.value;
	const emailValue = emailField.value;
	const nameDescNode = document.getElementById("nameDesc");
	const emailDescNode = document.getElementById("emailDesc");

	// Cleanup inline error messages
	if (nameDescNode) {
		nameDescNode.parentNode.removeChild(nameDescNode);
	}
	if (emailDescNode) {
		emailDescNode.parentNode.removeChild(emailDescNode);
	}
	
	// Display error message if form is invalid
	if (nameValue === "" || emailValue === "") {
		formMessageHolder.innerHTML = `
			<p>Please review the form and fix the following errors:</p>
			<ul>
				${nameValue ? "" : "<li>The name field must be filled in.</li>"}
				${emailValue ? "" : "<li>The e-mail field must be filled in.</li>"}
			</ul>
		`;

		if (nameValue === "") {
			createErrorDescription("nameDesc", nameField, "The name field must be filled in.");
		}

		if (emailValue === "") {
			createErrorDescription("emailDesc", emailField, "The e-mail field must be filled in.");
		} 

		// Set focus on the first invalid field
		nameValue === "" ? nameField.focus() : emailField.focus();
	} else {
		// Display success message if form was sent successfully
		formMessageHolder.innerHTML = "<p>The form was sent successfully!</p>";
	}
});

// Helper method to create an field error message
const createErrorDescription = (name, field, message) => {
	var newNode = document.createElement("div");
	newNode.setAttribute("id", name);
	newNode.classList.add("field-error");
	field.setAttribute("aria-describedby", name);
	newNode.innerHTML = message;
	field.after(newNode);
};